由于机载SAR多普勒参数受载机不稳定飞行和复杂地形影响明显,目前仍缺少有效的矢量估计法。本文对POS和DEM数据及其误差对机载多普勒参数的影响进行了分析,以距离-共面方程构建的SAR几何关系为基础,在POS和DEM数据支持下,建立了一种多普勒参数矢量估计法,并通过仿真对提出的方法进行了验证和分析。理论和仿真表明,本文方法在高山地形、不稳飞行及大斜视角等复杂条件下,亦能够为机载SAR瞬时多普勒中心提供高精度估计。
It is difficult to estimate the Doppler frequency and modulating rate for airborne SAR by using traditional vector method due to instable flight and complex terrain. In this paper, it is qualitatively analyzed that the impacts of POS, DEM and their errors on airborne SAR Doppler parameters. Then an innovative vector method is presented based on the range-coplanarity equation to estimate the Doppler centroid taking the POS and DEM as auxiliary data. The effectiveness of the proposed method is validated and analyzed via the simulation experiments. The theoretical analysis and experimental results show that the method can be used to estimate the Doppler centroid with high accuracy even in the cases of high relief, instable flight, and large squint SAR.
[1] LI Wenchao, YANG Jianyu, WU Junjie, et al. A Geometry-based Doppler Centroid Estimator for Bistatic Forward-looking SAR[J]. Geoscience and Remote Sensing Letters, 2012, 9(3): 388-392.
[2] KONG Y K, CHO B L, KIM Y S. Ambiguity-free Doppler Centroid Estimation Technique for Airborne SAR Using the Radon Transform[J]. IEEE Transactions on Geoscience and Remote Sensing, 2005, 43(4): 715-721.
[3] CHENG Chunquan, ZHANG Jixian, HUANG Guoman, et al. Range-cocone Equation with Doppler Parameter for SAR Imagery Positioning[J]. Journal of Remote Sensing, 2013,17(6):1444-1458. (程春泉, 张继贤,黄国满, 等. 考虑多普勒参数的SAR影像距离: 共面方程及其定位[J]. 遥感学报, 2013, 17(5): 1444-1458.)
[4] LONG T, LU Z, DING Z G, et al. A DBS Doppler Centroid Estimation Algorithm Based on Entropy Minimization[J]. IEEE Transactions on Geoscience and Remote Sensing, 2011, 49(10): 3703-3712.
[5] ZHU S, LIAO G, QU Y, et al. Unambiguous Doppler Centroid Estimation Approach for Synthetic Aperture Radar Data Based upon Compressed Signal Magnitude[J]. Radar, Sonar & Navigation, 2011, 5(3): 341-348.
[6] RANEY R K. A Comment on Doppler FM Rate[J].International Journal of Remote Sensing, 1987, 8(7): 786-799.
[7] BAMLER R. Doppler Frequency Estimation and the Cramer-Rao Bound[J]. IEEE Transactions on GRS, 1991, 29(3): 385-389.
[8] ZHAO Bingji, QI Xiangyang, SONG Hongjun, et al. Accurate Doppler Parameters Estimation of Geo-SAR Based on Elliptical Orbit[J]. Journal of Electronics & Information Technology, 2012, 34(11): 2642-2647. (赵秉吉,齐向阳,宋红军, 等. 基于椭圆轨道的Geo-SAR 精确多普勒参数解析计算方法[J]. 电子与信息学报, 2012, 34(11): 2642-2647.)
[9] YU Mingcheng, XU Jia, PENG Yingning, et al. Estimation of Doppler Parameters for Large Squint SAR[J]. Modern Radar. 2008, 30(2): 44-48. (于明成, 许稼, 彭应宁, 等. 大斜视SAR的多普勒参数估计[J]. 现代雷达, 2008, 30(2): 44-48.)
[10] MOSTAFA M M R, HUTTON J. Direct Positioning and Orientation Systems: How Do They Work? What is the Attainable Accuracy?[C]//Proceedings of American Society of Photogrammetry and Remote Sensing (ASPRS) Annual Meeting. ST Louis: ASPRS, 2001: 18-27.
[11] ZHAO Lijian, CHENG Xinwen, LI Yingcheng, et al. Accuracy Check and Analysis of LiDAR Elevation Data[J]. Geospatial Information, 2009, 7(1): 58-60. (赵礼剑, 程新文, 李英成, 等. 机载LiDAR点云高程数据精度检核及误差来源分析[J]. 地理空间信息, 2009, 7(1): 58-60.)
[12] APPLANIX. POSAV Specification[EB/OL]. 2012[2013-11-21]. http://www.applanix.com/media/downloads/ products/specs/ POSAVSPECS0812. pdf.
[13] JIN Guowang, ZHANG Wei, XIANG Maosheng, et al. A New Calibration Algorithm of Interferometric Parameters for Dual Antenna Airborne InSAR[J]. Acta Geodaetica et Cartographica Sinica. 2010, 39(1): 76-81. (靳国旺, 张薇, 向茂生, 等. 一种机载双天线InSAR干涉参数定标新方法[J]. 测绘学报, 2010, 39(1): 76-81.)
[14] CUMMING I G, WONG F H. 2005. Digital Processing of Synthetic Aperture Radar Data: Algorithm and Implementatoin. Boston: Artech House Publishers.
[15] CHENG Chunquan, ZHANG Jixian, DENG Kazhong, et al. Range-coplanarity Equation for Radar Geometric Imaging[J]. Journal of Remote Sensing, 2012, 16(1): 38-49. (程春泉, 张继贤, 邓喀中, 等. 雷达影像几何构像距离-共面方程[J]. 遥感学报, 2012, 16(1): 38-49.)
[16] YUAN Xiuxiao, ZHANG Xueping, FU Jianhong. Transformation of Angular Elements Obtained via a Position and Orientation System in Gauss-Kruger Projection Coordinate System[J]. Acta Geodaetica et Cartographica Sinica, 2011, 40(3): 338-344. (袁修孝, 张雪萍, 付建红. 高斯-克吕格投影坐标系下POS角元素的转换方法[J]. 测绘学报, 2011, 40(3): 338-344.)
[17] LIU Guangyan, HUANG Shunji. New Applications of Doppler Frequency in Squint SAR Imaging Processing[J]. Acta Electronica Sinica, 2003, 31(6): 829-832. (刘光炎, 黄顺吉. 斜视成像处理中多普勒频率的新应用[J]. 电子学报, 2003, 31(6): 829-832.)
[18] MERCER B. National and Regional Scale DEMs Created from Airborne InSAR[C]//Proceedings of International Archives of Photogrammetry, Remote Sensing and Spacial Information Sciences: Photogrammetic Image Analysis. Munich: [s.n.], 2007: 49-56.
[19] ZHANG Yanbin, GUO Huadong, HAN Chunming. High Precision DEM Generation Using Airborne Dual-antenna InSAR Data: A Case Study of Large Hilly Areas[J]. Remote Sensing for Land and Resources, 2014, 26(1): 97-102. (张延冰, 郭华东, 韩春明. 利用机载双天线InSAR数据生成高精度DEM的试验研究: 以大面积丘陵地区为例[J]. 国土资源遥感, 2014, 26(1): 97-102.)
